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A295346 Number of n X 2 0..1 arrays with each 1 horizontally or vertically adjacent to 0, 2 or 3 1s. 3
3, 8, 20, 51, 132, 341, 883, 2293, 5964, 15532, 40495, 105670, 275929, 720907, 1884293, 4926808, 12885462, 33707537, 88191612, 230773219, 603933677, 1580626249, 4137115442, 10829006070, 28346361639, 74202762892, 194246812311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A295352.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 4*a(n-1) - 3*a(n-2) - 4*a(n-4) - a(n-5) + a(n-6).

Empirical g.f.: x*(3 - 4*x - 3*x^2 - 5*x^3 + x^5) / ((1 - 3*x + x^2)*(1 - x - x^2 - 2*x^3 - x^4)). - Colin Barker, Feb 26 2018

EXAMPLE

Some solutions for n=5:

..0..0. .0..1. .1..0. .1..1. .0..0. .1..0. .0..0. .1..0. .1..0. .0..0

..0..0. .0..0. .0..1. .1..1. .0..0. .0..0. .0..0. .0..1. .0..1. .0..0

..1..1. .0..0. .0..0. .0..0. .0..1. .1..1. .1..1. .1..0. .1..0. .1..0

..1..1. .0..0. .1..0. .0..1. .1..0. .1..1. .1..1. .0..0. .0..1. .0..0

..1..1. .0..1. .0..1. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..0

CROSSREFS

Cf. A295352.

Sequence in context: A174198 A077997 A294407 * A027220 A305823 A333679

Adjacent sequences:  A295343 A295344 A295345 * A295347 A295348 A295349

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 20 2017

STATUS

approved

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Last modified July 5 03:05 EDT 2020. Contains 335457 sequences. (Running on oeis4.)